Rechargeable lithium batteries, recently under extensive development, exhibit battery performance characteristics, such as charge-discharge voltage, charge-discharge cycle life characteristics and storage characteristics, which depend largely upon the types of the electrodes used.
In accordance with the previous finding of the present applicant, an electrode having, on a current collector, a thin film of active material that stores and releases lithium, such as an amorphous or microcrystalline silicon thin film, exhibits a high charge-discharge capacity and shows superior charge-discharge cycle characteristics. This electrode has such a structure that the thin film of active material is divided into columns by gaps formed therein in a manner to extend in its thickness direction and the columnar portions are at their bottoms adhered to the current collector. This structure enables the electrode to exhibit superior charge-discharge cycle performance characteristics, because the spaces provided to surround those columnar portions serve to relax a stress engendered as the thin film expands and shrinks during charge-discharge cycles and thus lessen a stress that acts to separate the thin film of active material from the current collector.
However, the relationship between nonaqueous electrolyte and charge-discharge cycle characteristics has not been fully investigated for rechargeable lithium batteries using such an electrode.